Re: [PATCH v3 0/4] kmod: help make deterministic

From: Petr Mladek <pmladek@suse.com>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Jessica Yu <jeyu@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Shuah Khan <shuah@kernel.org>,
	Rusty Russell <rusty@rustcorp.com.au>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Josh Triplett <josh@joshtriplett.org>,
	martin.wilck@suse.com, Michal Marek <mmarek@suse.com>,
	hare <hare@suse.com>,
	rwright@hpe.com, Jeff Mahoney <jeffm@suse.com>,
	David Sterba <DSterba@suse.com>,
	Filipe Manana <fdmanana@suse.com>, NeilBrown <neilb@suse.com>,
	Guenter Roeck <linux@roeck-us.net>,
	rgoldwyn@suse.com,
	Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>,
	Heinrich Schuchardt <xypron.glpk@gmx.de>,
	Aaron Tomlin <atomlin@redhat.com>,
	Miroslav Benes <mbenes@suse.cz>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Ingo Molnar <mingo@redhat.com>, Alan Cox <alan@linux.intel.com>,
	"Ted Ts'o" <tytso@mit.edu>, Greg KH <gregkh@linuxfoundation.org>,
	linux-kselftest@vger.kernel.org,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 0/4] kmod: help make deterministic
Date: Tue, 27 Jun 2017 10:13:39 +0200	[thread overview]
Message-ID: <20170627081339.GC7071@pathway.suse.cz> (raw)
In-Reply-To: <20170627002744.GP21846@wotan.suse.de>

On Tue 2017-06-27 02:27:44, Luis R. Rodriguez wrote:
> On Tue, Jun 27, 2017 at 12:44:42AM +0200, Luis R. Rodriguez wrote:
> > On Mon, Jun 26, 2017 at 11:37:36PM +0200, Jessica Yu wrote:
> > > +++ Kees Cook [20/06/17 17:23 -0700]:
> > > > On Tue, Jun 20, 2017 at 1:56 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> > > > > On Fri, May 26, 2017 at 02:12:24PM -0700, Luis R. Rodriguez wrote:
> > > > > > Luis R. Rodriguez (4):
> > > > > >   module: use list_for_each_entry_rcu() on find_module_all()
> > > > > >   kmod: reduce atomic operations on kmod_concurrent and simplify
> > > > > >   kmod: add test driver to stress test the module loader
> > > > > >   kmod: throttle kmod thread limit
> > > > > 
> > > > > About a month now with no further nitpicks. What tree should these changes
> > > > > go through if there are no issues? Andrew's, Jessica's ?
> > > > 
> > > > Seems like going through Jessica's would make the most sense?
> > > 
> > > Would be happy to take patches 01 (which I need to anyway), 02,
> > > possibly 04 if decoupled from the test driver (03).
> > 
> > Feel free to decouple it, but note that then the commit log must then be
> > changed. My own take is this fix is not so critical as it is a corner case, so
> > I have instead preferred to couple in the test case and respective fix
> > together. I'll leave it up to you how to proceed.
> 
> Note: Linus noted swait is actually very special use-case [0] so I'd hate to
> add a new use case not vetted for. This use case on kmod.c really does *not*
> require anything but a simple wait though, so really am inclined to let that
> through unless I hear back...
> 
> [0] https://lkml.kernel.org/r/20170627001534.GK21846@wotan.suse.de

Heh, I was not aware of this special case either. The welcoming
comment of the swait API confused me as well.

In this light, I suggest to switch the patch to using the normal wait API.

Best Regards,
Petr